1. Field of the Invention
The present invention relates to a mobile transmission system having a voice processing device.
2. Description of the Related Art
In a conventional mobile transmission system, since data volume is tremendously increased if usual voice signals used in public telephone lines are used, as they are, in a wireless range, a voice processing device is employed to convert voice signals to coded voice signals in order to compress the data volume, wherein wireless transmission is carried out.
FIG. 1 is a block diagram of a conventional mobile transmission system.
As shown in FIG. 1, the conventional mobile transmission system mainly consists of an exchange controlling station 11, wireless controlling stations 12, voice processing devices 13, and base stations 14. The exchange controlling station 11 mutually connects a plurality of wireless controlling stations 12 to the main network 15 of public telephone lines. Furthermore, the wireless controlling station 12 controls wireless channels of the base stations 14.
In the conventional mobile transmission system, the voice processing devices 13 are connected to the wireless controlling stations 12, wherein voice signals are converted by controlling the wireless controlling stations 12.
Herein, in line with the recent popularization of mobile transmission and progress of mobile transmission technologies, requests for a new control occur in the mobile transmission system. As one of the requests, a voice processing device is connected to the exchange controlling station, wherein it is considered that, by causing the exchange controlling station to control the voice processing devices, voice processing devices which are, respectively, connected to a plurality of wireless controlling stations are collected at one point, in order to increase efficiency of voice processing.
However, in the existing mobile transmission system, if voice processing devices also are connected to the exchange controlling station, the voice processing devices at the wireless controlling station side will be made useless. Furthermore, once the voice processing devices at the wireless controlling station side are disused, they will be no longer used in a case where the voice processing devices are desired to be utilized at the wireless controlling station side due to changes in the transmission system in the future.